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Catastrophe,hysteresis and bifurcation of mode transition in scramjet engines and its model

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Science China(Technological Sciences) 2009年第6期52卷 1543-1550页

作者： YU DaRen CUI Tao bao wen Harbin Institute of Technology Harbin 150001China

This paper describes a class of nonlinear phenomena existing in the hypersonic flow and supersonic combustion process of scramjet engines:catastrophe,hysteresis and bifurcation,and further finds out the general rules(topological invariance)for the stability boundaries of mode transition in scramjet *** this topological invariance,a topological approach is put forward to model the stability boundaries,which may contribute to a complexity reduction of high-dimensional modeling when con-sidering more perturbation parameters,and help to explore the physical laws of the nonlinear ***,this paper interprets the characteristic of combustion mode transition based on the cusp topological model in singular theories,and observes the bifurcation characteristic in com-bustion mode ***,a modeling approach is proposed to mathematically describe the stability boundaries of combustion mode transition in scramjet engines,and the model has high ac-curacy comparing to the simulation data,which proves the validation of the basic ideas proposed in this ***,future research directions are proposed.

关键词： scramjet engine catastrophe bifurcation model

Deterioration in Heat Transfer of Endothermal Hydrocarbon Fuel

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Journal of Thermal Science 2011年第2期20卷 173-180页

作者： Weixing Zhou wen bao Jiang Qin Yunfeng Qu Harbin Institute of Technology Harbin China 150001

Numerical studies under supercritical pressure are carried out to study the heat transfer characteristics in a single-root coolant channel of the active regenerative cooling system of the scramjet engine, using actual physical properties of pentane. The relationships between wall temperature and inlet temperature, mass flow rate, wall heat flux, inlet pressure, as well as center stream temperature are obtained. The results suggest that the heat transfer deterioration occurs when the fuel temperature approaches the pseudo-critical temperature, and the wall temperature increases rapidly and heat transfer coefficient decreases sharply. The decrease of wall heat flux, as well as the increase of mass flow rate and inlet pressure makes the starting point of the heat transfer deterioration and the peak point of the wall temperature move backward. The wall temperature increment induced by heat transfer deterioration decreases, which could reduce the severity of the heat transfer deterioration. The relational expression of the heat transfer deterioration critical heat flux derives from the relationship of the mass flow rate and the inlet pressure.

关键词： supercritical pressure pentane heat transfer deterioration numerical study

Experimental Study on Measurement and Calculation of Heat Flux in Supersonic Combustor of Scramjet

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Journal of Thermal Science 2015年第3期24卷 254-259页

作者： ZHANG Cong YAO Zhanli QIN Jiang bao wen Harbin Institute of Technology

An experimental measurement and calculation method which consist of thermal response model, convergence criteria and control algorithms, is proposed in this paper for the determination of heat flux in a scramjet combus- tot. Numerical simulations are done to evaluate the effectiveness of the proposed method, and experiments are made in the direct-connect hydrocarbon fueled scramjet combustor of Mach-6 flight for different equivalence ra- tios. The distribution of heat flux along the axial and circumferential directions can be obtained using the pro- posed method. The distribution of heat flux is uneven which is caused by the aerodynamic heating, combustion heat release and changes of section area, and the peak heat flux can be more than 2MW/m^2 during the experi- ments. Heat flux increases with the increase in equivalence ratio for the same Mach number. And axial distribu- tion of heat flux is uniform for different equivalence ratios. In addition, the combustion heat release area of the combustion chamber can therefore be concluded which is useful for guiding the structural design of the thermal protection system.

关键词： Scramjet Heat flux Thermal response model Thermal protection

Dynamic Characteristics of Hydrocarbon Fuel within the Channel at Supercrit- ical and Pyrolysis Condition

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Journal of Thermal Science 2017年第6期26卷 560-569页

作者： YU Bin ZHOU Weixing QIN Jiang bao wen Harbin Institute of Technology 150001 Heilongjiang China

Regenerative cooling with fuel as the coolant is used in the scramjet engine. In order to grasp the dynamic cha- racteristics of engine fuel supply processes, this article studies the dynamic characteristics of hydrocarbon fuel within the channel. A one-dimensional dynamic model was proved, the thermal energy storage effect, fuel volume effect and chemical dynamic effect have been considered in the model, the ordinary differential equations were solved using a 4th order Rungc-Kutta method. The precision of the model was validated by three groups of expe- rimental data. The effects of input signal, working condition, tube size on the dynamic characteristics of pressure, flow rate, temperature have been simulated. It is found that cracking reaction increased the compressibility of the fuel pyrolysis mixture and lead to longer responding time of outlet flow. The responding time of outlet flow can reach 3s when tube is 5m long which will greatly influence the control performance of the engine thrust system. Meanwhile, when the inlet flow rate appears the step change, the inlet pressure leads to overshoot, the overshoot can reach as much as 100%, such highly transient impulse will result in detrimental effect on fucl pump.

关键词： dynamic characteristics n-Decane supercritical pyrolysis

Gain Scheduling Control of Nonlinear Shock Motion Based on Equilibrium Manifold Linearization Model

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Chinese Journal of Aeronautics 2007年第6期20卷 481-487页

作者： Cui Tao Yu Daren bao wen Yang Yongbin College of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China

The equilibrium manifold linearization model of nonlinear shock motion is of higher accuracy and lower complexity over other models such as the small perturbation model and the piecewise-linear model. This paper analyzes the physical significance of the equilibrium manifold linearization model, and the self-feedback mechanism of shock motion is revealed. This helps to describe the stability and dynamics of shock motion. Based on the model, the paper puts forwards a gain scheduling control method for nonlinear shock motion. Simulation has shown the validity of the control scheme.

关键词： shock motion equilibrium manifold linearization gain scheduling control

A novel blind deconvolution algorithm using single frequency bin

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1271-1276页

作者： ZHANG Gui-bao LI Jia-wen LI Cong-xin National Die ＆ Mold CAD Engineering Research Center Shanghai Jiao Tong University Shanghai 200030 China

Former frequency-domain blind devolution algorithms need to consider a large number of frequency bins and recover the sources in different orders and with different amplitudes in each frequency bin,so they suffer from permutation and amplitude indeterminacy troubles. Based on sliding discrete Fourier transform,the presented deconvolution algorithm can directly recover time-domain sources from frequency-domain convolutive model using single frequency bin. It only needs to execute blind sepa-ration of instantaneous mixture once there are no permutation and amplitude indeterminacy troubles. Compared with former algorithms,the algorithm greatly reduces the computation cost as only one frequency bin is considered. Its good and robust per-formance is demonstrated by simulations when the signal-to-noise-ratio is high.

关键词： Blind deconvolution Single frequency bin Convolutive mixture

Feedback of Efficient Shock Acceleration on Magnetic-field Structure Inside Young Type Ia Supernova Remnants

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Research in Astronomy and Astrophysics 2024年第6期24卷 234-244页

作者： Jun-Yu Shen Bi-wen bao Li Zhang Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China Key Laboratory of Statistical Modeling and Data Analysis of Yunnan Province Yunnan UniversityKunming 650091China

Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic field(BMF) topologies:a uniform and a turbulent *** density distribution and magnetic-field characteristics of our benchmark SNR are studied with two-dimensional cylindrical magnetohydrodynamic *** γ_(eff)is considered,we find that:(1) the two-shock structure shrinks and the downstream magnetic-field orientation is dominated by the Rayleigh–Taylor instability structures;(2) there exists more quasi-radial magnetic fields inside the shocked region;and (3) inside the intershock region,both the quasi-radial magnetic energy density and the total magnetic energy density are enhanced:in the radial direction,with γ_(eff)=1.1,they are amplified about 10–26 times more than those with γ_(eff)=5/*** in the angular direction,the total magnetic energy densities could be amplified about 350 times more than those with γ_(eff)=5/3,and there are more grid cells within the intershock region where the magnetic energy density is amplified by a factor greater than 100.

关键词： methods:numerical ISM:magnetic fields ISM:supernova remnants magnetohydrodynamics(MHD)

Joining of dissimilar metals between magnesium AZ31B and aluminum A6061-T6 using galvanized steel as a transition joining layer

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Journal of Iron and Steel Research International 2022年第4期29卷 677-686页

作者： Wei Li Jing-huan Chang bao-feng wen Rui Cao State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metal Lanzhou University of TechnologyLanzhou 730050GansuChina Department of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050GansuChina

A galvanized steel is used to join Mg AZ31B alloy and Al A6061-T6 alloy as a joining transition layer by cold metal transfer(CMT)***,to optimize the process variables,extensive welding tests were performed by a design of experiment ***,microstructures,joining mechanisms and tensile properties were characterized and *** indicated that Mg and Al alloys can be joined by using galvanized steel as a joining transition layer and cold metal transfer welding *** formed joint is called as a Mg–steel–Al CMT *** using galvanized steel transition joining layer,Mg–Al brittle intermetallics Al12Mg17 and Al3Mg2 were *** properties of Mg–steel–Al CMT joints have been improved after optimizing the welding *** strength of Mg–steel–Al CMT joint is comparable to those of Al–Al joint and Mg–Mg *** strength of Mg–steel–Al CMT joint can reach 100%that of Al–Al joint and Al–steel joint,and reach 90%that of Mg–Mg joint and Mg–steel *** optimized Mg–steel–Al CMT welded joint with galvanized steel transition layer is fractured at the heat affected zone of Al base metal rather than at the weld-brazed interface,due to softening of Al base metal.

关键词： Cold metal transfer Mg alloy Al alloy Galvanized steel Transition joining layer Dissimilar metal joining

Spatial impact of organic matters from point sources on stream water quality

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Mining Science and Technology 2009年第2期19卷 256-261页

作者： LIU wen-bao CHEN Dong-mei Department of Geography Queen＇s University Kingston Ontario K7L 3N6 Canada

To get a better understanding of the spatial impact of organic discharges on stream water quality,a "scenario-testing" approach was proposed to examine how a change in plant treatment efficiency would affect dissolved oxygen(DO) concentration along a *** "upper-lower" boundary technique was applied to conduct sensitivity analysis to observe the responses of DO concentration to different DO-related *** results show a non-linear discrepancy of biochemical oxygen demand(BOD) and DO concentration among different treatment scenarios,which indicates the higher the efficiency of the plant treatment,the shorter the time the stream needs to *** sensitivity analysis reveals that the larger the amount of the waste discharge,the more sensitive the BOD to the biological removal *** addition,the DO is more sensitive to the biological removal parameter than to the reaeration parameter.

关键词： waste treatment dissolved oxygen biological oxygen demand scenario testing sensitivity analysis